Hello guys, need your help regarding our aux boiler burner. Saacke SKVJM36. When i open the burner, fuel is all over the place. There was no leak from the pipe, some fuel are coming back to the primary air fan. But burner is working in normal condition. Can be started easily in automatic and emergency mode. Belt is good, current of motor is okay. I tried to adjust the primary air to give more air and reduce fuel pressure but still some fuel are still going back to the impeller of primary air. Did this happen to anyone?

...wha?

FO solenoid stuck open and putting fuel in when you don't want it to?
Check and clean the FO VVs.

Seems there's no prob with solenoid valves because there's no leakage when burner is not running. This happens only when boiler is running and after a while fuel accumulate all over inside the burner. My observation is that fuel is coming back to the part of primary air(which should not be) and it supply air with some fuel.

I'll attach what it looks like whenever i open the burner even for using it only for 1-2 days.

Problem solved, replaced atomizer cup and fuel distributor.